The changing engagement point could indicate your clutch plates have worn and that springs are weak. Time for service!
Don't chance it ... a clutch job is the cheapest and easiest job you can do on your bike. Easier than changing a tire. A mechanic can do the whole job in an hours time.
Even not knowing the job, you could do it in 2 or 3 hours taking your time, using the workshop manual or on online tutorial. So simple. I've not done a CRF250 but I'm betting it's not far off from outline below:
Before you start ... soak new clutch plates in fresh oil ... only need soak 1/2 hour or so.
Drain Oil
Pull engine case cover, note bolt order, length of bolts.
remove 4 to 6 bolts holding clutch plates and Pressure disc (pressure plate)
remove bolts and springs
Remove Pressure plate (plan to replace it)
Remove OLD clutch plates ... NOTE order and position, set aside.
Install NEW clutch plates in CORRECT order, alternating a friction plate with a steel plate. Chances are good you only need replace Friction plates, steel plates are probably fine for re-use if not warped at all. (money saved)
Install new Pressure plate (if clutch is slipping, PP can get scored, best a new one)
Install NEW springs, install bolts (this bit is important!*)
Tighten up bolts evenly
replace engine case cover
refill with FRESH oil.
Adjust free play, test ride.
*If used hard in heat what can happen is clutch springs will lose tension and actually SHRINK! You can measure yours against spec to see how worn they are. Short springs (worn out) mean clutch can then slip, wearing clutch plates quickly. Fresh Springs are ESSENTIAL for long clutch life.
Pressure plate may be OK for re-use, but if any scoring, replace!
Clutch parts are pretty cheap. A genuine Honda work shop manual may cost more.
Don't use Car type synthetic oil. If you use synthetic oil, make sure it is OK for the wet clutch in a motorcycle. Use No oil that contains Friction Modifiers, clutch will slip, ruined!
Any standard oil of correct weight is OK, or any Semi Synthetic.
Be careful with FULL synthetic ... must be Moto specific. If in doubt, don't use it.